Madpk always structures its training sessions thusly:
1. Warm-up
2. Conditioning
3. Skills work/drills
4. Obstacle coursing/follow-the-leader/"flow" work
5. Free time to work on personal goals/skills, play on obstacles, etc.
6. Stretch/cooldown (sometimes this part doesn't always happen like it should)
The first part of our warmup is always the same; it's sort of our "official" Madpk warmup to get the blood flowing and the joints loose. The second part will always have footwork/agility, QM, and upper and lower body exercises as well as dynamic hip opening stretches. We may emphasize one of these parts more or less depending on what our training objective is for the day and what that means for the body.
Conditioning will be directly related to our training objective for the day and/or week (we have weekly challenges at Madpk). Sometimes we will individualize certain things if individual people need to condition certain things or are lacking in certain strength/speed/coordination areas.
Skills work is simple drilling/breaking down of a particular skill that relates to our training objective for the day/week (e.g. a certain vault, balance, precisions, footwork, wall climbs, jump distance, etc. Lots of skills to choose from here!)
Follow-the-leader/obstacle coursing is pretty much what it says. We run through a route in our environment, getting over obstacles in whatever ways we can.
Free time is for people to just play and work on individual skills. We are trying to cultivate a very strong work ethic in this part of our training because often people will spend time socializing. This will come over time, mostly through modeling by us of the behavior we want. (I will talk more on modeling later).
Stretching/cooldown is done together, following a pretty set format, although we sometimes emphasize some stretches over others as needed depending on what we've worked on for the day.
My suggestions are to establish your training objectives for the year, then break that down into monthly training objectives, then weekly, then daily. From there, you will have a single purpose for each lesson, and then you can plan your lessons "backwards" from that. Your objectives should include general conditioning/fitness benchmarks, parkour skills benchmarks, and "conceptual" benchmarks (e.g. understanding the ideas of safety, conditioning/training, respect, relationship to fear, fitness, etc.) that you want them to achieve by the end of the school year. Then from there you work backwards to try to ensure that your daily training sessions get them there one step at a time.
I have a huge article (okay actually it was an email to Zac when he asked a similar question) about how to plan lessons/training sessions. If you'd like, I can dig it up for you and paste it here.
The other big piece is modeling. People learn far more by what they see/watch you do than by what you say. If you want people to work hard, you will have to work hard yourself. If you want people to eat well and train seriously, then you have to live that yourself. Basically the best way to be an effective teacher of traceurs is to be an exemplary traceur yourself. And I don't mean necessarily in your skills, but in your approach to the discipline. You absolutely must put safety and respect and hard work first, because if people have internalized these qualities, then teaching them the physical skills will be much easier. This is what I mean by modeling the behavior you want. You have to establish your training culture from the very beginning, through your actions and the tone of your first training session, and then live it the rest of the year. To quote Harry Wong, regarded as a master educator by pretty much every teacher in the world, "If you screw up the first day, you're dead meat the rest of the year."
Lastly, people learn parkour by
doing parkour. If you could learn parkour just by hearing about it, we'd all be as awesome as David Belle by now. So you have to demonstrate fully what you want people to do, and then let them try it out. They will screw up, and it will not be pretty. Give them only one or two pointers at a time, and let them work on those. Obviously if what they are doing is not safe you have to stop them. But if they are just messing up because it's tricky/new for them, let them keep at it, and let them work it out on their own. They also will do better "getting it" if you *show* them again, rather than just telling them. But let them/make them DO the movement, and keep doing it either until they get it or until they are showing mental fatigue. Then have them move on to something else and come back to the other movement later if they want.
Remind them and encourage them to practice. Newbies feel uncomfortable trying something for the first time and if it's mostly young guys (which it probably will be) there will be this macho thing they will likely try to hide behind to hide their insecurity at looking like a dork trying something new.

So have them do stuff in small groups or tell them to "spread out and try this on your own. Do at least 5 of them on each side and I will come around and help you." If they are all busy working on getting their 5, they will realize that no one else is watching them and they will feel more comfortable trying. But get them moving and doing it! Otherwise their insecurity will have them all standing around and they won't get anywhere. Also on this same note, give them a specific number to do. Show them a skill, then say, "Do 5 of these on your own" (or 20 or however many). Otherwise they may do one feeble attempt and then feel silly and give up. You want to reinforce practice.
Also, I assume that since this is an official club you will have a teacher or school official working with you (
please be sure you do, given liability, etc.). Make sure you have your teacher/club advisor on board with you. He/she will have excellent insight into how to set up training sessions, since it's basically what teachers do.

So work closely with that person to get ideas and also to establish a level of supervision/authority to your club.
Hopefully this is helpful. Good luck!